1. Field of the Invention
The present invention relates to a device for forming the shed in a Jacquard-type weaving loom, to a process for mounting such a device and to a weaving loom equipped with such a shed-forming device or mounted in accordance with such a process. The invention is more particularly centered on the vertical actuation, in phase opposition, of the two series of blades or knives which ensure control of the hooks of a weave system.
2. Description of the Related Art
In a shed-formation device, hooks are disposed in parallel rows separated from one another by spaces, in each of which a knife moves vertically. This knife is most often supported by one of two griffe frames. Each frame is suspended from levers animated by an oscillating movement so as to lower and rise alternately, it being observed that the vertical displacements of the knives are effected simultaneously, in opposite directions, in order to open the shed for insertion of the weft yarn.
In conventional systems, such as disclosed in particular in French Patent Application FR-A-2 669 650, a single shaft is provided, which is connected to the main shaft of the weaving loom and which extends over the whole width of the frame of the system. In the vicinity of each of its ends, this shaft, which is animated by a movement of continuous rotation, is equipped with two adjacent systems of cams or eccentrics adapted to transform this continuous rotation into a reciprocating rotation in order to give the lever which bears the griffe frames the desired lowering and rising movement. These conventional systems present a certain number of drawbacks. The presence of the mechanisms for transforming the continuous movement into reciprocating movement substantially increases the cost of the assembly, at the same time as increasing the dimensions of the actuation mechanism and hindering accessibility to the hooks of the system. Furthermore, these transformation mechanisms complicate the general structure of the frame.
In addition, the driven shaft of the weaving loom on which the shed-forming device must be installed, may be located to the left or to the right of the loom. It is usual to provide that the shed-forming device be fitted on looms with driven shaft to the left or to the right. However, it may happen that the weaver using the loom decides to change the type or supplier of loom while maintaining his choice concerning the shed-forming device, with the result that it is sometimes necessary to change the entry side of the movement in the shed-forming device. With the known devices, this modification is long and complex. In particular, it induces considerable interventions on the peripheral members of the system such as the chassis and the transmission elements.